1. Field of the Invention
The present invention relates to writing instruments and, in particular, to capless writing instruments in which a nib is retractable and protractible.
2. Description of the Related Art
Conventional writing instruments can typically include a body for holding a supply of ink, a tip adapter for securing a writing tip, and a cap fitting on the tip adapter for protecting the writing tip and for preventing the ink from drying out. To use the writing instrument, the cap is removed from the tip adapter and, in some cases, can be stored on a back of the body. To store the writing instrument, the cap is replaced on the tip adapter.
Writing instruments such as highlighters, markers, and dry-erase markers may use volatile inks. Accordingly, these types of markers have tightly sealed caps to minimize evaporation of the inks. Failure to replace the cap tightly can result in the evaporation of the ink solvents, thereby reducing the life span of the marker.
A capped writing instrument with volatile ink also requires two-hand operation for removing and replacing its cap. A retractable ball-point pen is also known in the art. However, the retractable ball-point pen has ink of a lesser volatility, and its mechanism would allow more volatile ink to dry out even if the bin is retracted. One specific example of a writing instrument that attempts to address this problem is shown in U.S. Pat. No. 6,033,141 to Blaustein et al. in which a seal used in the writing instrument. Other retractable instruments with volatile inks have been known, but in general, these instruments have failed to meet the needs of consumers for an inexpensive and reliable writing instrument.
In view of the foregoing, there remains a need in the art for an inexpensive retractable writing instrument which is able to reliable and adequately seal a nib when not in use to minimize evaporation of volatile marker and highlighter inks. The present invention satisfies one or more of these needs.